$-4kl - 5km - 9k + 9 = -6l + 7$ Solve for $k$.
Combine constant terms on the right. $-4kl - 5km - 9k + {9} = -6l + {7}$ $-4kl - 5km - 9k = -6l - {2}$ Notice that all the terms on the left-hand side of the equation have $k$ in them. $-4{k}l - 5{k}m - 9{k} = -6l - 2$ Factor out the $k$ ${k} \cdot \left( -4l - 5m - 9 \right) = -6l - 2$ Isolate the $k$ $k \cdot \left( -{4l - 5m - 9} \right) = -6l - 2$ $k = \dfrac{ -6l - 2 }{ -{4l - 5m - 9} }$ We can simplify this by multiplying the top and bottom by $-1$. $k= \dfrac{6l + 2}{4l + 5m + 9}$